Spontaneous Bacterial Peritonitis (SBP)

Spontaneous Bacterial Peritonitis (SBP)

Nolan R. King, MD

Table of Contents

Definitions
Etiology
Presentation and Diagnosis
Treatment

Definitions

Spontaneous Bacterial Peritonitis (SBP): Infection of the Peritoneum without an Intraabdominal Surgically Treatable Source

  • Also Referred to as “Primary Bacterial Peritonitis”
  • Generally Involves Infection of Ascites Fluid

Secondary Bacterial Peritonitis: Infection of the Peritoneum with an Intraabdominal Surgically Treatable Source

  • Less Common (5-15%) than SBP

Bacteriascites: Bacterial Colonization of Ascites Fluid without an Inflammatory Reaction

Etiology

Spontaneous Bacterial Peritonitis (SBP)

  • Cirrhosis Increases Risk Due to Impaired Host Defenses
    • Phagocyte Dysfunction
    • Complement Deficiency
    • Increased Free Iron for Growth (Normally Inhibited by Unsaturated Transferrin)
  • Bacteria Seeds by Translocation in the Gut or From Another Infected Site
  • Can Be Seeded by Paracentesis Introducing Bacteria into Ascites
  • Microbiology:
    • Usually a Single Organism
    • Most Common Organisms:
      • Escherichia coli (37-70% – Most Common)
      • Klebsiella (10-17%)
      • Pneumococci
      • Proteus spp.
      • Enterococcus
      • Pseudomonas
    • Most Common Organisms in Peds: Pneumococcal and Streptococcal

Secondary Bacterial Peritonitis 

  • Causes:
    • Bowel Perforation – Most Common Secondary Cause
    • Appendicitis
    • Cholecystitis
    • Colitis/Diverticulitis
    • Severe Pancreatitis
    • Bowel Obstruction with Strangulation
    • Iatrogenic
      • Anastomotic Leak
      • Endoscopic Perforation
      • Enterotomy
      • Infected Foreign Body
    • Peritoneal Dialysis
    • Intraabdominal Malignancy
    • Trauma
  • Microbiology:
    • Usually Polymicrobial
    • Most Common Organism in Peritoneal Dialysis: Staphylococcus epidermidis

Presentation and Diagnosis

Presentation

  • Fever
  • Abdominal Pain
  • Diarrhea
  • Nausea and Vomiting
  • Encephalopathy/Confusion
  • Peritoneal Abdominal Exam – Severe Tenderness, Guarding, Rebound, and Rigidity
  • Can Cause Sepsis with Tachycardia and Hypotension
  • Paracentesis with Cloudy Fluid Output

Traditional Signs May Be Masked in Patients with Cirrhosis Making Diagnosis Difficult – Requires a High Index of Suspicion

High Risk for Hepatorenal Syndrome

Diagnosis

  • Diagnosis is Primarily Made by Paracentesis
    • PMNL ≥ 250 is Diagnostic
  • Additionally Send Paracentesis Fluid for Culture to Guide Antibiotic Therapy
  • Should Obtain an Abdominal CT to Evaluate for Secondary Sources

It Can Be Difficult to Distinguish Spontaneous Bacterial Peritonitis (SBP) from Secondary Causes – SBP Can Present with Critical Illness, Peritoneal Abdominal Exam, and CT Showing Free Fluid (Ascites) and Pneumoperitoneum (From Recent Paracentesis)

Treatment

Primary Treatment: Paracentesis (“Tap Until Dry”) and Antibiotics

IV Albumin Can Potentially Decrease Mortality, Particularly in Patients with Renal Dysfunction (Debated)

Antibiotic Options

  • Cefotaxime – High Levels in Ascitic Fluid
  • Ceftriaxone
  • Fluoroquinolones (Ciprofloxacin)
  • *Secondary Causes Require Broader Antibacterial Coverage Such as Cefotaxime and Metronidazole

Secondary Causes Generally Require Surgical Source Control

  • CAUTION: Patients with SBP that Receive Unnecessary Exploratory Laparotomy Have High Mortality Rates (Up to 80%)

SBP with Peritoneal Dialysis (PD Catheter)

  • Initial Treatment: Intraperitoneal Antibiotics for 2 weeks (Better Than IV)
  • If Fails: Remove Catheter
  • *Fungal Infection Requires Immediate Catheter Removal

Prognosis in SBP

  • High Mortality if Treated Late (20-40%)
  • Best Predictors of Mortality: Renal Dysfunction and MELD Score
  • Low Mortality if Treatment is Initiated Early

Prophylaxis

  • Indications:
    • Any History of SBP
    • Cirrhosis with Variceal or Other GI Bleeding
    • Cirrhosis with Ascitic Fluid Protein < 1.5 g/dL and Renal Impairment or Liver Failure
  • Antibiotics: Trimethoprim-Sulfamethoxazole (Bactrim/TMP-SMX) or Fluoroquinolones (Ciprofloxacin/Norfloxacin)